Hydraulic vibrator

ABSTRACT

The present invention relates to an improved hydraulic vibrator of the type having a fixed vertical piston member supported in a frame. The piston member is comprised of a pair of oppositely extending rods connected to a centrally disposed drive piston and a reaction mass is reciprocally disposed around the drive piston forming a hydraulic cylinder so that when hydraulic fluid is introduced to the cylinder relative to the drive piston the reaction mass is reciprocated. By the present invention, one of the rods connected to the drive piston is provided with an upwardly facing annular shoulder thereby forming a single acting piston, and a downwardly facing annular shoulder is provided in the reaction mass positioned to form a hydraulic biasing cylinder around the single acting piston whereby hydraulic fluid may be introduced to said biasing cylinder to bias the weight of said reaction mass. Port means for introducing hydraulic fluid to said biasing cylinder are provided connected to said biasing cylinder and to a source of constant pressure hydraulic fluid.

United States Patent [1 Fair et a1.

[451 Ju1yl7, 1973 Filed:

HYDRAULIC VIBRATOR Inventors: Delbert W. Fair, J. H. Miller, Jr.,

both of Ponca City, Okla.

City, Okla.

Oct. 7, 1971 Appl. No.: 187,476

Assignee: Continental Oil Company, Ponca [52] US. Cl. 91/216 B, l81/.5 H [51] Int. Cl. F0lb 15/00 [58] Field of Search 91/216 B; 92/117, 92/110,111, 85, 134, 143; 181/15 H [56] References Cited UNITED STATES PATENTS 2,068,045 l/1937 Wohlmeyer 91/216 B 615,245 12/1898 Browne 91/216 B 2,186,266 l/l940 Onions 1 92/8 1,441,097 1/1923 Laughlin 91/216 B 1,122,591 12/1914 Hamilton 92/216 B 1,506,219 8/1924 Clark 91/216 B 3,267,715 8/1966 Williamson 92/134 FOREIGN PATENTS OR APPLICATIONS 21,649 8/1964 Japan 92/143 F ree reet Primary Examiner-Allan D. Herrmann Assistant Examiner-R. 1-1. Lazarus Attorney-Joseph C. Kotarski, WilliamJ. Miller, et al.

[ ABSTRACT The present invention relates to an improved hydraulic vibrator of the type having a fixed vertical piston member supported in a frame. The piston member is comprised ofa pair of oppositely extending rods connected to a centrally disposed drive piston and a reaction mass is reciprocally disposed around the drive piston forming a hydraulic cylinder so that when hydraulic fluid is introduced to the cylinder relative to the drive piston the reaction mass is reciprocated. By the present invention, one of the rods connected to the drive piston is provided with an upwardly facing annular shoulder thereby forming a single acting piston, and a downwardly facing'annular shoulder is provided in the reaction mass positioned to form a hydraulic biasing cylinder around the single acting piston whereby hydraulic fluid may be introduced to said biasing cylinder to bias the weight of said reaction mass. Port means for introducing hydraulic fluid to said biasing cylinder are provided connected to said biasing cylinder and to a source of constant pressure hydraulic fluid 4 Claims, 1 Drawing Figure PATENIEU JUL 1 71m CONSTANT HYDRAULI PRES E C SUP Y BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the art of seismographic surveying, and more particularly, but not by way of limitation, to an improved hydraulic seismic vibrator of the type used to generate continuous seismic signals.

2. Description of the Prior Art Many various seismic surveying systems have been developed which utilize a continuous wave seismic signal generated in the earth by a vibrator. Such vibrators generally comprise a base plate for engaging the surface of the earth, a reaction mass and a linear actuator, usually hydraulic, for reciprocating the reaction mass relative to the base plate at a desired frequency.

A particularly satisfactory hydraulic seismic vibrator or transducer which has heretofore been developed and used utilizes a fixed double-rod-end piston member and a reaction mass reciprocally disposed around the piston member forming a hydraulic cylinder whereby hydraulic fluid may be introduced to the cylinder to reciprocate the reaction mass. A conventional hydraulic fluid control system is utilized to alternately port hydraulic fluid under pressure to the two sides of the drive piston in the cylinder so that the reaction mass is moved from a central position in one direction, back to the central position, from the central position in the other direction, back to the central position, and so on. Depending upon the particular size and design of the vibrator, the weight of the reaction mass may vary from several hundred pounds to several thousand pounds. In order to offset the weight of the reaction mass, a differential pressure must be maintained across the piston which results in less net driving force available for moving the reaction mass in one direction than the other. This unbalanced force condition has been found to cause serious problems, among which is the generation of undesirable harmonic vibrations.

Heretofore, in order to offset or bias the weight of the reaction mass in a manner independent from the drive cylinder, auxiliary hydraulic cylinders connected to the outside of the reaction mass or machined into the reaction mass positioned away from the center line of the reaction mass have been used. It has been found that the use of such auxiliary biasing hydraulic cylinders often brings about excessive wear in the vibrator apparatus due to the unbalanced forces being applied to the reaction mass. Further, maintenance problems associated with the auxiliary hydraulic cylinders are numerous.

By the present invention an improved hydraulic vibrator is provided wherein the weight of the reaction mass is biased without producing unbalanced forces on the reaction mass and wherein the equipment and maintenance problems associated with auxiliary hydraulic biasing cylinders are obviated.

SUMMARY OF THE INVENTION draulic cylinder so that when hydraulic fluid is intro-' duced to the cylinder relative to the drive piston the reaction mass is reciprocated. By the present invention one of the rods of the piston member is provided with an upwardly facing annular shoulder to form a single acting piston. A downwardly facing annular shoulder is provided in the reaction mass and positioned to form a hydraulic biasing cylinder around the single acting piston whereby hydraulic fluid may be introduced to the biasing cylinder to bias the weight of the reaction mass. Port means for introducing hydraulic fluid to the biasing cylinder are provided connected to the biasing cylinder and to a source of constant pressure hydraulic fluid.

It is, therefore, a general object of the present invention to provide an improved hydraulic vibrator.

A further object of the present invention is the provision of an improved hydraulic vibrator of the type having a fixed vertical piston member and a reaction mass reciprocally disposed around the piston member wherein the weight of the reaction mass is biased by a hydraulic biasing cylinder which :is positioned concentric with the axis of the reaction mass thereby producing no unbalanced forces on the reaction mass.

Another object of the present invention is the provision of an improved hydraulic vilbrator wherein auxiliary hydraulic cylinder apparatus for biasing the weight of the reaction mass and maintenance problems associated therewith are obviated.

Other and further objects, features and advantages of the present invention will become apparent from the following detailed description thereof given for the purpose of disclosure when taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a side sectional view partially in diagrammatic form of the improved hydraulic vibrator of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing, the improved hydraulic vibrator of the present invention is illustrated and generally designated by the numeral 10. The apparatus 10 basically comprises a frame 12 having a fixed double-rod-end piston member 14 attached thereto and a reaction mass 16 reciprocally mounted around the piston member 14.

The frame 12 may take a variety of forms, but generally includes a base plate 18 and an upper frame member 20 with an enclosure 22 connected therebetween.

The double-rod-end piston member 14 includes a lower rod 24, the end of which is connected to the base plate 18, an upper rod 26, the end of which is connected to the upper frame member 20, and a centrally disposed double acting drive piston 28. The drive piston 28 is slidably received within a cylinder 30 formed within the reaction mass 16. The piston 28 may be of any suitable conventional construction and may be provided with piston rings or the like to insure a sliding, fluid tight seal within the interior of the cylinder 30. The cylinder 30 may be formed within the reaction mass 16 by a plurality of sleeve inserts and sealing rings in a conventional manner.

Hydraulic fluid is introduced to the cylinder 30 alternately on opposite sides of the drive piston 28 by way of hydraulic fluid ports 32 and 34 disposed on opposite side of the piston 28. The ports 32 and 34 are formed in the rods 24 and 26, respectively, and are connected to a pair of passageways 36 and 38 also formed within the piston member 14. That is, the hydraulic fluid ports 32 are connected to one of the passageways 36 or 38 and the hydraulic fluid ports 34 are connected to the other of the passageways 36 and 38. The passageways 36 and 38 are connected by a pair of complementary passageways 40 and 42 disposed in the upper frame member to a conventional hydraulic fluid servo or control valve 44 which is part of a conventional hydraulic drive and control system. The control valve 44 is activated by a suitable electric control system to cause hydraulic fluid under pressure to alternately pass to and from the cylinder 30 by way of the passageways 36 and 38 and hydraulic fluid ports 32 and 34 which in turn causes the reaction mass 16 to be reciprocated.

By the present invention, in order to offset or bias the weight of the reaction mass 16, a'biasing hydraulic cylinder, generally designated by the numeral 46, is provided between one of the rods 24 or 26 of the piston member 14 and the reaction mass 16. For example, as shown in the drawing, the uppermost portion of the rod 26 is of a smaller diameter than the lowermost portion thereby providing an upwardlyfacing annular shoulder 48. The reaction mass 16 is provided with a downwardly facing annular shoulder 50 which is positioned with respect to the upwardly facing shoulder 48 of the rod 26 to form a biasing cylinder 46. The downwardly facing shoulder 50 may be provided by the lower end of a conventional annular sleeve insert 51 secured within the reaction mass 16 in a conventional manner. As will be understood, the upwardly facing annular shoulder 48 of the rod 26 functions as a single acting piston with the annular space between the shoulder 48 of the rod 26 and the shoulder 50 of the sleeve insert 51 forming the hydraulic biasing cylinder 46. One or more hydraulic fluid ports 52 are provided in the rod 26 above the shoulder 48 for the introduction of hydraulic fluid to the biasing cylinder 46, and a passageway 54 is provided connecting the port or ports 52 to 4 a source of constant pressure hydraulic fluid by way of the control valve 44.

In operation of the apparatus 10, hydraulic fluid is introduced to the cylinder 30 alternately on opposite sides of the drive piston 28 thereby causing the reaction mass 16 to reciprocate relative to the base plate 18. Simultaneously, constant pressure hydraulic fluid is .ported to and from the biasing hydraulic cylinder 46 thereby biasing the weight of the reaction mass 16. As will be understood, the relative areas of the annular shoulders 48 and are sized such that the weight of the reaction mass 16 is offset by theupward force generated in the cylinder 46 by the constant pressure hydraulic fluid ported thereto.

1 The present invention brings about many advantages as compared to similar apparatus heretofore used wherein the weight of the reaction mass is biased by one or more auxiliary hydraulic cylinders offset from the center line of the reaction mass. A partial list of these advantages is as follows:

1. Auxiliary hydraulic cylinders utilized heretofore for biasing or offsetting the weight of the reaction mass require hydraulic hoses and other control equipment which in turn cause maintenance problems. By the present invention, a biasing hydraulic cylinder is provided which requires no extra hydraulic hoses, seals and mechanical parts.

2. By the present invention, the biasing cylinder is concentrically positioned with the main hydraulic drive cylinder and as a result there are no offset forces applied to the reaction mass.

3. In the hydraulic system presently used for operating vibrators of the type herein described constant pressure hydraulic fluid is available from the main hydraulic fluid supply system. This fluid is free to flow in both directions and may be utilized with no extra equipment required in accordance with the present invention for providing a constant biasing force to the reaction mass.

Other advantages of the present invention will be readily apparent to those skilled in the art. While presently preferred embodiments of the invention have been described for the purpose of this disclosure, numerous changes in the details of construction and the arrangement of parts can be made. For example, while a vibratorapparatus of the fixed piston type with hydraulic fluid ported through the piston member has been described, the invention is equally applicable to a variety of other vibrator apparatus having other porting systems and piston-reaction mass arrangements which are encompassed within the spirit of the invention described herein and the scope of the appended claims.

What is claimed is:

1. In a hydraulic vibrator having a fixed vertical piston member comprised of a pair of oppositely extending rods connected to a centrally disposed drive piston and a reaction mass reciprocally disposed around the drive piston forming a hydraulic cylinder so that when hydraulic fluid is introduced to the cylinder relative to the drive piston the reaction mass is reciprocated, the improvement comprising:

one of said rods including an upwardly facing annular shoulder thereby forming a single acting piston;

said reaction mass including a downwardly facing annular shoulder positioned to form a hydraulic biasing cylinder around said single acting piston whereby hydraulic fluid may be introduced to said biasing cylinder to bias the weight of said reaction mass; and

means including ports for introducing hydraulic fluid to said biasing cylinder connected to said biasing cylinder and to a source of constant pressure hydraulic fluid, said pressure being sufficient to center said reaction mass with respect to said centrally disposed drive piston.

2. The apparatus of claim 1 wherein said port means for introducing hydraulic fluid to said biasing cylinder comprises:

at least one hydraulic fluid port disposed in said piston member and positioned for the introduction of hydraulic fluid into said biasing cylinder; and

a vertical passageway formed within said piston member connected to said hydraulic fluid port and to said source of constant pressure hydraulic fluid.

3. An improved hydraulic vibrator which comprises:

a frame;

a vertical double-rod-end piston member having an upper rod the end of which is attached to said frame and which includes an upwardly acting piston, a lower rod the end of which is attached to said frame and a centrally disposed drive piston;

a reaction mass reciprocally disposed around the piston member and forming a hydraulic drive cylinder 6 around said centrally disposed drive piston and a means for connecting said biasing cylinder to a hydraulic biasing cylinder around said upwardly urc of constant pressure hydraulic fluid. acting Piston; 4. The apparatus of claim 3 wherein said port means P W mean for introducing hydraulic fluid to Said for introducing hydraulic fluid to said biasing cylinder drive cylinder to reciprocate the reaction mass rel- 5 comprises:

ative to the drive piston connected to said drive cylinder and to a Source of hydraulic fluid; at least one hydraulic fluid port disposed in said PIS- port means for introducing hydraulic fluid to said bimerllber f"? positlonefl the lmrofijuction of asing cylinder relative to said upwardly acting pishydrauhc b'asmg cyl'nder' and ton, said hydraulic fluid having sufflcient pressure 10 a vertical passageway formed within Said Piston so that the weight of said reaction mass is biased member connected to said hydraulic fluid P and centrally with respect to said centrally disposed to said source of constant pressure hydraulic fluid. drive piston; and 

1. In a hydraulic vibrator having a fixed vertical piston member comprised of a pair of oppositely extending rods connected to a centrally disposed drive piston and a reaction mass reciprocally disposed around the drive piston forming a hydraulic cylinder so that when hydraulic fluid is introduced to the cylinder relative to the drive piston the reaction mass is reciprocated, the improvement comprising: one of said rods including an upwardly facing annular shoulder thereby forming a single acting piston; said reaction mass including a downwardly facing annular shoulder positioned to form a hydraulic biasing cylinder around said single acting piston whereby hydraulic fluid may be introduced to said biasing cylinder to bias the weight of said reaction mass; and means including ports for introducing hydraulic fluid to said biasing cylinder connected to said biasing cylinder and to a source of constant pressure hydraulic fluid, said pressure being sufficient to center said reaction mass with respect to said centrally disposed drive piston.
 2. The apparatus of claim 1 wherein said port means for introducing hydraulic fluid to said biasing cylinder comprises: at least one hydraulic fluid port disposed in said piston member and positioned for the introduction of hydraulic fluid into said biasing cylinder; and a vertical passageway formed within said piston member connected to said hydraulic fluid port and to said source of constant pressure hydraulic fluid.
 3. An improved hydraulic vibrator which comprises: a frame; a vertical double-rod-end piston member having an upper rod the end of which is attached to said frame and which includes an upwardly acting piston, a lower rod the end of which is attached to said frame and a centrally disposed drive piston; a reaction mass reciprocally disposed around the piston member and forming a hydraulic drive cylinder around said centrally disposed drive piston and a hydraulic biasing cylinder around said upwardly acting piston; port means for introducing hydraulic fluid to said drive cylinder to reciprocate the reaction mass relative to the drive piston connected to said drive cylinder and to a source of hydraulic fluid; port means for introducing hydraulic fluid to said biasing cylinder relative to said upwardly acting piston, said hydraulic fluid having sufficient pressure so that the weight of said reaction mass is biased centrally with respect to said centrally disposed drive piston; and means for connecting said biasing cylinder to a source of constant pressure hydraulic fluid.
 4. The apparatus of claim 3 wherein said port means for introducing hydraulic fluid to said biasing cylinder comprises: at least one hydraulic fluid port disposed in said piston member and positioned for the introduction of hydraulic fluid into said biasing cylinder; and a vertical passageway formed within said piston member conNected to said hydraulic fluid port and to said source of constant pressure hydraulic fluid. 